milestone

A milestone is a significant event or point in a project, program, or process that marks progress toward a goal. The term originates from road-building traditions where a stone or marker would be set up to indicate distance along a route. Milestones are used to convey progress to stakeholders and to orient teams around critical points.

In project management and software development, a milestone is a specific point in time or natural event that signifies the completion of a major phase or deliverable. It differs from a task in that it is not usually work to be done but a point where a decision is made or a review is conducted. Milestones are often used to trigger approvals, assess risk, or release resources.

Types include calendar milestones (date-based), deliverable milestones (a fixed artifact is completed), capability milestones (a required capability is achieved), and external milestones (dependent on third-party delivery). Examples: completing requirements specification, obtaining stakeholder sign-off, finishing beta testing, or launching a product.

Milestones are commonly represented in project roadmaps and milestone charts; in Gantt charts they are shown as diamonds or flags. They help communicate status to customers and sponsors, enable dependency management, and facilitate risk assessment. However, focusing too much on milestones can neglect ongoing work; milestones should reflect meaningful progress and be aligned with strategy rather than simply be dates.

Related concepts include checkpoints, gates, deliverables, and key performance indicators. The term is used across industries such as construction, software development, research, and product management.